Head suspensions are well known and commonly used within dynamic magnetic or optical information storage devices or drives with rigid disks. The head suspension is a component within the disk drive that positions a head slider having a magnetic or optical read/write head over a desired position on the storage media where information is to be retrieved (read) or transferred (written). Head suspensions for use in rigid disk drives typically include a load beam that generates a spring force and that includes a gimbal region or supports a flexure to which a head slider is to be mounted. Head suspensions are normally combined with an actuator arm or E-block to which a mounting region of the load beam is mounted with a base plate so as to position (by linear or rotary movement) the head suspension, and thus the head slider and read/write head, with respect to data tracks of the rigid disk. The rigid disk within a disk drive rapidly spins about an axis, and the head slider is aerodynamically designed to “fly” on an air bearing generated by the spinning disk.
The head suspension typically includes electrical traces that electrically connect the read/write head to control electronics mounted external to the head suspension. The traces may be attached to the components of the head suspension, such as the load beam and/or flexure, or they may be integrally formed with the components. The traces typically terminate in slider bond pads at a distal end of the head suspension in the head slider mounting region. The read/write head is then electrically connected to the traces through bonding of the head slider to the slider bond pads. This bonding may be accomplished through various methods, but most typically through gold ball bonding or solder ball bonding.
Gold ball bonding is accomplished by contacting a tool to the head suspension to support the back side of the bonding pads during ultrasonic placement of the gold ball between the head slider and trace bonding pads. Gold ball bonding requires and produces very little heat and results in little or no shrinkage of the gold ball after the bonding procedure. However, contact of the tool to the head suspension may cause distortion in or damage to the head suspension components. In addition, in some head suspension configurations an opening in the head suspension components, such as the load beam, near the bonding region is required so that the tool can contact the necessary parts of the head suspension. As a result, the load beam must be wider, which causes the head suspension to have lower resonant frequencies than are desired for optimum performance of the head suspension.
Solder ball bonding is accomplished by applying heat at or near a solder ball positioned at the head slider and trace bonding pads. The heat melts the solder ball. The solder wets to the head slider and trace bonding pads, and then shrinks upon cooling. Solder ball bonding does not require contact with the head suspension, which reduces the likelihood of damage to or distortion of the head suspension due to contact by a tool. Without the tool, the need for an opening in some load beam configurations is eliminated, and thus the load beam may be narrower and thus may have better resonant performance. In addition, bonding attachments by solder ball bonding are easier to rework, when necessary, than gold ball bonding attachments. However, shrinkage of the solder ball may cause distortion in the head suspension components at or near the bonding region, which may then affect head suspension characteristics, such as static attitude. The ability to use solder ball bonding, but without the resulting distortion, would be the preferable head slider bonding situation.